From 7175f647f576a4d613928a87dc7140280df4217f Mon Sep 17 00:00:00 2001
From: jsmall-nvidia <jsmall@nvidia.com>
Date: Mon, 26 Jun 2023 18:11:02 -0400
Subject: Multiple cast issue fix (#2940)

* Small fixes and improvements around reflection tool.

* Make PrettyWriter printing a class.

* WIP parens casting issue.

* Fix issue with multiple casts.

* Match previous location point for casting, with 'fast' path.

* Removed logic to output the found decl, as not needed to construct ExplicitCastExpr.
---
 source/slang/slang-parser.cpp                   | 26 ++++++++++++++++++-------
 tests/bugs/parens-cast-issue.slang              | 21 ++++++++++++++++++++
 tests/bugs/parens-cast-issue.slang.expected.txt |  4 ++++
 3 files changed, 44 insertions(+), 7 deletions(-)
 create mode 100644 tests/bugs/parens-cast-issue.slang
 create mode 100644 tests/bugs/parens-cast-issue.slang.expected.txt

diff --git a/source/slang/slang-parser.cpp b/source/slang/slang-parser.cpp
index fdc5c19b5..d606698a1 100644
--- a/source/slang/slang-parser.cpp
+++ b/source/slang/slang-parser.cpp
@@ -4362,7 +4362,7 @@ namespace Slang
             nullptr, // no semantics visitor available yet
             name,
             parser->currentScope);
-        if(!lookupResult.isValid() || lookupResult.isOverloaded())
+        if (!lookupResult.isValid() || lookupResult.isOverloaded())
             return false;
 
         return _isType(lookupResult.item.declRef.getDecl());
@@ -4370,7 +4370,7 @@ namespace Slang
 
     static bool peekTypeName(Parser* parser)
     {
-        if(!parser->LookAheadToken(TokenType::Identifier))
+        if (!parser->LookAheadToken(TokenType::Identifier))
             return false;
 
         auto name = parser->tokenReader.peekToken().getName();
@@ -5597,14 +5597,26 @@ namespace Slang
         case TokenType::LParent:
             {
                 Token openParen = parser->ReadToken(TokenType::LParent);
-                Expr* typeExpr = nullptr;
-                if (peekTypeName(parser) && parser->LookAheadToken(TokenType::RParent))
+
+                // Only handles cases of `(type)`, where type is a single identifier,
+                // and at this point the type is known
+                if (peekTypeName(parser) && parser->LookAheadToken(TokenType::RParent, 1))
                 {
-                    TypeCastExpr* tcexpr = parser->astBuilder->create<ExplicitCastExpr>();
-                    parser->FillPosition(tcexpr);
-                    tcexpr->functionExpr = typeExpr;
+                    // Get the identifier for the type
+                    const Token typeToken = advanceToken(parser);
+                    // Consume the closing `)`
                     parser->ReadToken(TokenType::RParent);
 
+                    auto varExpr = parser->astBuilder->create<VarExpr>();
+                    varExpr->scope = parser->currentScope;
+                    varExpr->loc = typeToken.loc;
+                    varExpr->name = typeToken.getName();
+
+                    TypeCastExpr* tcexpr = parser->astBuilder->create<ExplicitCastExpr>();
+                    tcexpr->loc = openParen.loc;
+
+                    tcexpr->functionExpr = varExpr;
+
                     auto arg = parsePrefixExpr(parser);
                     tcexpr->arguments.add(arg);
 
diff --git a/tests/bugs/parens-cast-issue.slang b/tests/bugs/parens-cast-issue.slang
new file mode 100644
index 000000000..2cfe603c8
--- /dev/null
+++ b/tests/bugs/parens-cast-issue.slang
@@ -0,0 +1,21 @@
+//TEST(compute):COMPARE_COMPUTE_EX:-slang -compute -shaderobj
+//TEST(compute,vulkan):COMPARE_COMPUTE_EX:-vk -slang -compute -shaderobj
+
+//TEST_INPUT:ubuffer(data=[0 0 0 0], stride=4):out,name outputBuffer
+RWStructuredBuffer<int> outputBuffer;
+
+[numthreads(4, 1, 1)]
+void computeMain(uint3 dispatchThreadID : SV_DispatchThreadID)
+{
+	uint tid = dispatchThreadID.x;
+    int idx = (int)tid;
+    
+    float q = (idx * 0.5);
+ 
+    int x = (uint)(int)q;
+    
+    // This combination of casts and parenthesis used to cause issues. 
+    int z = ((uint)(int)q);
+    
+ 	outputBuffer[tid] = z + x;
+}
\ No newline at end of file
diff --git a/tests/bugs/parens-cast-issue.slang.expected.txt b/tests/bugs/parens-cast-issue.slang.expected.txt
new file mode 100644
index 000000000..3333a969d
--- /dev/null
+++ b/tests/bugs/parens-cast-issue.slang.expected.txt
@@ -0,0 +1,4 @@
+0
+0
+2
+2
-- 
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